1. Field of the Invention
The present invention relates to systems and methods for measuring and monitoring physiological changes in a body.
2. Description of the Relevant Art
Surgery involving the gastrointestinal tract is commonly performed for a variety of reasons. In many cases, gastrointestinal surgery involves the division of the gastrointestinal tract and removal of a segment of the gastrointestinal tract. When the gastrointestinal tract is divided and/or a segment of the gastrointestinal tract is removed, a subsequent re-connection is performed to restore gastrointestinal continuity using suture material, surgical stapling devices, and/or various reinforcing materials. This re-connection is referred to as a gastrointestinal anastomosis.
Anastomotic leak is a potentially devastating complication of esophagectomy that occurs in 3-25% of cases and results in mortality as high as 20-50%. Early diagnosis is critical to minimizing morbidity and mortality and for this reason it remains common practice to perform routine upper gastrointestinal (GI) contrast fluoroscopy after surgery to identify leaks before they present clinically. However, numerous studies have questioned the value of routine post-esophagectomy upper GI contrast fluoroscopy because of its low sensitivity in identifying anastomotic leak. In a prospective trial examining fluoroscopy using a water soluble contrast agent, the sensitivity for detection of an anastomotic leak was reported as only 40%. The addition of high-density barium may increase the sensitivity of upper GI fluoroscopy by 60%. Computed tomography scanning with aqueous enteral contrast has been proposed as an alternative to upper GI fluoroscopy but its utility may also be limited; one prospective study showed a sensitivity of only 73% for anastomotic leak for CT with enteral contrast. Upper gastrointestinal endoscopy has a reported sensitivity and specificity for anastomotic leak of 100% but since it requires an invasive procedure it is unlikely to be adopted as a routine post-operative diagnostic modality in all patients. Because of the lack of a sensitive, non-invasive study to identify anastomotic leak in post-esophagectomy patients, a significant number of leaks are not detected until they present clinically.
In summary, anastomotic leak is a major source of morbidity and mortality after upper gastrointestinal surgery that is most effectively treated when it is recognized early. However, no definitive diagnostic test for anastomotic leak exists at the current time and the sensitivity and specificity of the methods currently used have not been adequately determined. Moreover, in the medical literature, authors have pointed to the need for better definition of and identification of anastomotic leaks to improve the care of patients who undergo gastrointestinal surgery. Therefore, there is a recognized need for a device that would provide improved anastomotic leak detection.